Along with the producing technology development, the liquid crystal display has been become a widely used display device. The working principle of the liquid crystal display is based on the phenomenon that the alignment condition of liquid crystal molecules is changed by applying an electrical field to change the path of light passing through the liquid crystal molecules and the display effect of changing in light and shade is further achieved.
FIG. 1 is a diagram illustrating a unit circuit block of a thin film transistor liquid crystal display according to the prior art. The thin film transistor 11 is controlled by the voltage Vs of scanning line for switching the statuses of “on” and “off”. The voltage Vd of the data line is applied to a liquid crystal 12 located between a pixel electrode 131 and a common electrode 132 for changing the alignment condition of the liquid crystal 12 and further controlling the light penetrating degree of the liquid crystal molecules 12. Thus, the emissive intensity from a light source 14 at the back of the liquid crystal display will occur change while the light reaches to the eyes of a user for achieving the display effect of the changing in light and shade. The storage capacitance 15 is used for reinforcing the device characteristics.
The thin film transistor liquid crystal display is formed by producing a lot of arrays constructed by the unit circuit as shown in FIG. 1 on a display panel. However, some defects in the data or scanning lines are possible to occur by mistake or through carelessness. For ruling out the defects, a plurality of annular repair lines around an array are established in the layout of the current thin film transistor liquid crystal display. FIG. 2 is a top view illustrating a structure having a plurality of annular repair lines around the array of the thin film transistor liquid crystal display according to the prior art. As shown in FIG. 2, the array 21 has five annular repair lines 201, 202, 203, 204 and 205 therearound. When a data line 22 of the array 21 has a breaking point occurred, the regions 2011 and 2012 are welded and the regions 2013 and 2014 are cut by laser for achieving the repairing effect.
In addition, FIG. 4 is a schematic view illustrating a repair structure for a liquid crystal display according to a prior art. When a defect is discovered, a insulation layer 43 between a first metal layer 41 and a second metal layer 42 is needed to be destroyed by a laser. Subsequently, the first metal layer 41 is burned to melt, and the first metal layer 41 is welded with the second metal layer 42 to accomplish the repair.
Because the melting point of aluminum is in the range from about 550° C. to 660° C., aluminum is beneficial to the performance of welding. The first metal layer 41 is usually made of aluminum. However, due to the low melting point of aluminum, aluminum is easily splashed around when the welding is performed by the laser. Furthermore, a short circuit, a broken circuit, or a Schottky contact is happened to a contact point.
Thus, using the annular repair lines for repairing the defects according to the prior art has the following disadvantages:    (1) The signal transmission line is too long after being repaired, so a serious problem of RC time delay is easy to occur;    (2) A large area of panel is required to move for performing the repairing action, so the production efficiency will be decreased; and    (3) The structure of the repair lines according to the prior art occupies much area of panel, which decreases the utility rate of glass substrates.    (4) The structure of the repair lines according to the prior art easily causes a short circuit, a broken circuit, or a Schottky contact in a contact point.
Therefore, the purpose of the present invention is to develop a method to deal with the above situations encountered in the prior art.